• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.2
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• pp.17-23
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• 2000

Wireless link has high bit error rate compared with wired link and many users share this limited bandwidth. So it needs more powerful error control code and efficient media access control(MAC) to provide multimedia service reliably. In this paper we proposed efficient MAC frame format based on TDMA using mini-slot for request access. The number of mini-slots is variable based on the result of collision in the previous frame. This dynamic allocation of request mini-slots helps resolve the contention situation quickly and avoids the waste of bandwidth that may occur when there are several unneeded request mini-slots. The simulation results are also presented in terms of channel utilization, call blocking probability and cell transmission delay for mixed traffic environment.

• Convergence Security Journal
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• v.15 no.2
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• pp.11-17
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• 2015

According to NIA (National Information Society Agency) report, digital divide is a vicious circle which makes quality interval of human's life between people who have information and relatively not. Especially in a smart phone society, there is a big problem between disabled people and normal people. This paper suggests a braille keyboard system for the blind to solve these problems. It is designed for portable use, convenience and quick text typing based on bluetooth communication technique. In text input test, all texts (Korean, English, number) were accurately expressed and typing speed was about 22 [c/m](characters per a minute). Especially, we design text2voice function to provide more accurate key input system. Popular applications such as call, alarm, message, kakao talk, internet, music, were performed without carring problems using the proposed braille keyboard system. The proposed technique is thought to contribute to eliminating the digital divide through the expansion of smartphone users.

• Spatial Information Research
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• v.10 no.1
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• pp.61-76
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• 2002

Mobile map services using PDA are prevailing because of the rapid developments of techniques of the internet and handhold devices recently. While the volume of spatial data is tremendous and the spatial operations are time-intensive, the PDA has small size memory and a low performance processor. Therefore, the spatial index for PDA should be small size and efficiently filter out the candidate objects of spatial operation as well. This paper proposes a spatial index far PDA called MHF(Multilevel Hashing File). The MHF has simple structure for storage efficiency and uses a hashing technique, which is direct search method, for search efficiency. This paper also designs a compression technique for MBR. which occupies almost 80% of index data in the two dimensional case. We call it HMBR. Although the HMBR technique reduces the MB\ulcorner size to almost a third, it shows good filtering efficiency because of no information loss by quantization in case of small objects that occupy a major portion. Our experimental tests show that the proposed MHF index using HMBR technique is appropriate for PDA in terms of the size of index, the Number of MBR comparisons, the filtering efficiency and the execution time of spatial operations.

• Korean Journal of Agricultural Science
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• v.38 no.3
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• pp.583-591
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• 2011

Status survey on short-term agricultural machinery rental business was conducted to provide basic data for effective and sustainable implementation of the rental system. Selected survey samples were 34 rental management institutions such as city and county level government offices and agricultural technology development centers, and Primary Agricultural Cooperatives. Survey was conducted through mailing of questionnaire papers and direct interviews with the officers in charge of the agricultural machinery short-term rental management. Number of agricultural machinery retained by the 34 management institutions for the machinery rental business was 3,699, and numbers of the machinery were 1630 for upland crops, 929 for rice, 542 for orchard farming, 274 for animal husbandry, and 324 for common use. Regarding size of warehouse for rental agricultural machinery, 50% of the institutes were less than 660 $m^2$, 26.5% were greater than 993 $m^2$, and 23.5% were between 663 and 990 $m^2$. Institutes maintaining machinery washing facilities were only 10 (29%) among the 34 rental management institutions. Agricultural machinery rental business was advertised to farmers by 91% of the institutes, and the methods were leaflet (35.2%), village broadcasting (26.5%), call-up education (23.6%), and TV and radio (14.7%). Major contents of the advertisement were rental procedure (52.9%), rental machinery (26.5%), and rental cost (20.6%).

• Journal of the Korea Society of Computer and Information
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• v.16 no.12
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• pp.265-271
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• 2011

High-quality customized services demand was growing due to the increase of aging, extremely nuclear family, disaster vulnerable of society. Ambulance service is required of fast and professional rescue and emergency service because of preventable death rate such as acute diseases, cerebral and cardiovascular diseases, suicides, etc. was higher than in developed countries. First aid will be available using patients information when emergency occurs, before arriving at the hospital. And emergency department is equipped with that patient care can be prepared in advance, increase the efficiency of emergency care. We received a variety of complex emergency call using high social awareness of 119 number and propose an efficient emergency medical service advancement strategy building an integrated response system with relevant organization.

• Journal of the Korea Society of Computer and Information
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• v.16 no.4
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• pp.235-241
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• 2011

A large number of industry and trade circulation enterprises integrate logistics resource. They give links of product transport to some professional logistics enterprises in order to reduce costs. We call these professional logistics enterprises as the Third-party Logistics. As the development of the computer and internet, the suppliers, buyers and the Third-party Enterprises connect each other with internet. And different company use different management software, so heterogeneous data become a big problem of the information system for Third-party Enterprises. We built the logistics ontology with prot$\'{e}$g$\'{e}$, and translate it in OWL. We also built the rules for Logistics Ontology to improve the limitations of the OWL. Then we design the intelligent system for 3PL Enterprises Distribution Center based on Logistics Ontology and Logistics Rules. At final, we give an example to show the workflow visually.

• Korean Journal of Organic Agriculture
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• v.14 no.4
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• pp.433-443
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• 2006

With treatment of Kitosan, Wood vinegear and EM(effective microoganism) which farmers call it as substance in fertilizing, conditioning and disease control substances, authors in vestigated on microorganisms change in soil and ealy growth characteristics of tomato. The results were summarized as follows: Among foliar application of kitosan, wood vinegear and EM(effective microoganism) treatments diluted by chitosan 500 times solution level was effective considering growth of tomato as compared other dilutions and control plot. Change of microorganism number in the soil for cultivation of tomato was increased with microorganism treatment plot as compared with control plot. Specially chitosan 500 times solution level showes the most significant effect.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.953-958
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• 2015

Raspberry Pi is a credit card-sized computer with support for a large number of input and output peripherals. This makes it the perfect platform for interaction with many different devices and for usage in a wide range of applications. When combined with Wi-Fi, it can communicate remotely, therefore increasing its suitability for the construction of wireless sensor nodes. In addition, data processing and decision-making can be based on artificial intelligence, what is performed in developed testbed on the example of monitoring and determining the confidence of fire. In this paper, we demonstrated the usage of Raspberry Pi as a sensor web node for fire-safety monitoring in a building. When the UV-flame sensors detect a flame as thin as that of a candle, the Raspberry Pi sends a push-message to notify the assigned smartphone of the on-site situation through the GCM server. A mobile app was developed to provide a real-time video streaming service in order to determine a false alarm. If an emergency occurs, one can immediately call for help.

• Journal of Navigation and Port Research
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• v.31 no.5 s.121
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• pp.377-383
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• 2007

The number of calling ports has been decreased and the degree of inter- and intra-port competition has been increased, which is caused by the market trends that shipping liners have and operate their own terminals, strategic M & A frequency occurs among shipping liners, and container vessel size is increasing. The trends also cause shipping liners to change the evaluation factors for decision to call a particular port such as port preference, potential for growth, port competitiveness, etc. Since the decision of liners greatly influences the policies for port and terminal development, it is worth having interest in the evaluation factors. Therefore, this work intended to evaluate 8 major ports (Port of Singapore, Hong Kong, Shanghai, Busan, Rotterdam, Kaoshing, and Tokyo) with regard to liners' evaluation factors (calling port preference, potential for growth and port competitiveness) and to classify ports by similarity of evaluation factors with the methodologies of ANOVA analysis and Duncan test. The result shows implication for liners' viewpoint to evaluate major ports in the world.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11B
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• pp.1245-1253
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• 2009

Since 2000, the demand for multimedia content consumption has been continuously increasing. The research and standardization for the mobile broadcast service has been done to deliver multimedia contents to the huge number of users with the minimum cost. A few commercial services started after the related standards were released. We call this mobile broadcast service the 1st generation service. Now, many experts are researching and developing the technologies for 3Screens(TV, PC, and Mobile) Services that an user can enjoy multimedia contents at every place with the various networks and devices. To enable this service, two main technical areas exist. The first is a core network technology that can support the various access network and the second is a common application layer technology. To resolve these technical areas, we propose IMS(IP Multimedia Subsystem) based OMA BCAST(Open Mobile Alliance Mobile Broadcast Service Enabler Suite) as the technical solution for 3 Screen Services in the paper. In addition, we propose application layer multicast that is enable to implement IMS based OMA BCAST to the existing network with the minimum cost. Finally, we show how we can save the implementation cost of IMS based OMA BCAST with the simulation results.